Solubility of inorganic salts in sub- and supercritical hydrothermal environment: Application to SCWO processes

Supercritical water oxidation process (SCWO) is of great interest today in recycling toxic and/or complexed chemical wastes with very good efficiency. When reaching the critical conditions (374 degrees C, 22.1 MPa), polarity collapses and water becomes a very good solvent for organic compounds. However, these interesting properties for organics turn to be problematic regarding dissolved inorganics. Commonly present in the aqueous waste, those inorganics precipitate easily when approaching the critical domain, leading to plugs in the process. In order to better understand the precipitation of salts in supercritical water, their solubility behaviour is of main interest. However, lots of relevant data are still missing in the literature. The aim of this review is to summarise most of the existing data regarding salt solubility in sub- and supercritical water as well as the different set-ups and methods developed over the past 50 years, including predictive theoretical modelling. (C) 2016 Elsevier B.V. All rights reserved.